589-62-8Relevant academic research and scientific papers
Rhodium-catalyzed hydroboration reactions with sulfur and nitrogen analogues of catecholborane
Hadebe, Siphamandla W.,Robinson, Ross S.
, p. 4898 - 4904 (2006)
Rhodium-catalyzed hydroboration of 1-octene and trans-4-octene with sulfur- and nitrogen analogues of catecholborane are demonstrated with the use of in situ 11B NMR spectroscopy. Our study shows that the sulfur- and nitrogen analogues are significantly less prone to disproportionation than catechol, which results in enhanced yields of the desired compounds. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Reversal of Regioselectivity in Zinc-Dependent Medium-Chain Alcohol Dehydrogenase from Rhodococcus erythropolis toward Octanone Derivatives
Dhoke, Gaurao V.,Ensari, Yunus,Hacibaloglu, Dinc Yasat,G?rtner, Anna,Ruff, Anna Jo?lle,Bocola, Marco,Davari, Mehdi D.
, p. 2957 - 2965 (2020)
The zinc-dependent medium-chain alcohol dehydrogenase from Rhodococcus erythropolis (ReADH) is one of the most versatile biocatalysts for the stereoselective reduction of ketones to chiral alcohols. Despite its known broad substrate scope, ReADH only accepts carbonyl substrates with either a methyl or an ethyl group adjacent to the carbonyl moiety; this limits its use in the synthesis of the chiral alcohols that serve as a building blocks for pharmaceuticals. Protein engineering to expand the substrate scope of ReADH toward bulky substitutions next to carbonyl group (ethyl 2-oxo-4-phenylbutyrate) opens up new routes in the synthesis of ethyl-2-hydroxy-4-phenylbutanoate, an important intermediate for anti-hypertension drugs like enalaprilat and lisinopril. We have performed computer-aided engineering of ReADH toward ethyl 2-oxo-4-phenylbutyrate and octanone derivatives. W296, which is located in the small binding pocket of ReADH, sterically restricts the access of ethyl 2-oxo-4-phenylbutyrate, octan-3-one or octan-4-one toward the catalytic zinc ion and thereby limits ReADH activity. Computational analysis was used to identify position W296 and site-saturation mutagenesis (SSM) yielded an improved variant W296A with a 3.6-fold improved activity toward ethyl 2-oxo-4-phenylbutyrate when compared to WT ReADH (ReADH W296A: 17.10 U/mg and ReADH WT: 4.7 U/mg). In addition, the regioselectivity of ReADH W296A is shifted toward octanone substrates. ReADH W296A has a more than 16-fold increased activity toward octan-4-one (ReADH W296A: 0.97 U/mg and ReADH WT: 0.06 U/mg) and a more than 30-fold decreased activity toward octan-2-one (ReADH W296A: 0.23 U/mg and ReADH WT: 7.69 U/mg). Computational and experimental results revealed the role of position W296 in controlling the substrate scope and regiopreference of ReADH for a variety of carbonyl substrates.
Biocatalytic synthesis of non-vicinal aliphatic diols
Ebrecht, Ana C.,Aschenbrenner, Jasmin C.,Smit, Martha S.,Opperman, Diederik J.
supporting information, p. 439 - 445 (2021/01/29)
Biocatalysts are receiving increased attention in the field of selective oxyfunctionalization of C-H bonds, with cytochrome P450 monooxygenases (CYP450s), and the related peroxygenases, leading the field. Here we report on the substrate promiscuity of CYP505A30, previously characterized as a fatty acid hydroxylase. In addition to its regioselective oxyfunctionalization of saturated fatty acids (ω-1-ω-3 hydroxylation), primary fatty alcohols are also accepted with similar regioselectivities. Moreover, alkanes such as n-octane and n-decane are also readily accepted, allowing for the production of non-vicinal diols through sequential oxygenation. This journal is
The effects of metals and ligands on the oxidation of n-octane using iridium and rhodium “PNP” aminodiphosphine complexes
Naicker, Dunesha,Alapour, Saba,Friedrich, Holger B
, p. 282 - 289 (2020/12/01)
Ir and Rh “PNP” complexes with different ligands are utilized for the oxidation of n-octane. Based on the obtained conversion, selectivity, and the characterized recovered catalysts, it is found that the combination of Ir and the studied ligands does not promote the redox mechanism that is known to result in selective formation of oxo and peroxo compounds [desired species for C(1) activation]. Instead, they support a deeper oxidation mechanism, and thus higher selectivity for ketones and acids is obtained. In contrast, these ligands seem to tune the electron density around the Rh (in the Rh-PNP complexes), and thus result in a higher n-octane conversion and improved selectivity for the C(1) activated products, with minimized deeper oxidation, in comparison to Ir-PNP catalysts.
Efficient and region-selective conversion of octanes to epoxides under ambient conditions: Performance of tri-copper catalyst, [Cu3I(L)]+1 (L=7-N-Etppz)
Krupadam, Reddithota J.,Nagababu, Penumaka,Paul, Perala Sudheer,Reddy, Thatiparthi Byragi
, p. 742 - 745 (2021/09/28)
In this paper, is described the conversion of the octane group of hydrocarbons into industrially important epoxides using tri-copper catalyst, [Cu3I(L)]+1 (L=7-N-Etppz). The role of hydrogen peroxide as a sacrificial oxygen donor during catalytic conversion to epoxides has been investigated. The performance of the catalyst has been evaluated in terms of turnover numbers (TON) and turnover frequencies (TOF) reported in this article.
Flexible pincer backbone revisited: CuSNS complexes as efficient catalysts in paraffin oxidation
Bala, Muhammad D.,Friedrich, Holger B.,Soobramoney, Lynette
supporting information, (2021/07/16)
New Cu(II) complexes containing a set of tridentate hybrid SNS ligands were synthesised and fully characterised by IR, HRMS, elemental analysis and single-crystal X-ray diffraction. The complexes with the general formula Cu[bis(Rthioethyl)phenylamine]Cl2 (1); [R = methyl (a); ethyl (b); butyl (c); cyclohexyl (d) and t-butyl (e)] exhibited five-coordinate trigonal bipyramidal geometry around each Cu(II) centre in the solid-state with the S-donor atoms occupying the axial positions. However, complex 1b crystallised as a dimer bridged through a cuprate anion denoted as [1b(μ-CuCl4)1b]. Their application as catalysts in the oxidation of n-octane with hydrogen peroxide (H2O2) as an oxidant gave high substrate conversions to C-8 oxygenate products, mainly octanols, after reduction with PPh3. Notably, complex 1d produced the highest yield of 57% in 1 h reaction time at a catalyst concentration of 1 mol%. In general, high turnover numbers (2830–3180) were recorded for the 1/H2O2 catalytic systems with substantially high combined selectivity of 22–27% to 1-octanol and octanoic acid, which are the more desired products of n-octane oxidation resulting from its terminal carbon (C(1)) activation. The high activity of the catalysts is attributed to metal–ligand cooperative catalysis involving CuII-OOH intermediates as the active species modulated by the tridentate SNS ligands. In comparison with related complexes bearing N-donor atoms, the excellent catalytic performance of these series of CuSNS complexes highlights the critical role of the phenylamine N-donor atom.
Application of new Ru (II) pyridine-based complexes in the partial oxidation of n-octane
Chanerika, Revana,Friedrich, Holger B.,Shozi, Mzamo L.
, (2019/12/24)
Tridentate and bidentate Ru (II) complexes were prepared through reaction of four pyridine-based ligands: pyCH2N(R)CH2py {R = propyl, tert-butyl, cyclohexyl and phenyl; py = pyridine} with the [(η6-C6H6)Ru(μ-Cl)Cl]2 dimer. Crystal structures of the new terdentate Ru (II) complexes [Ru{pyCH2N(R)CH2py}C6H6](PF6)2 (R = C3H7 (1), C (CH3)3 (2), C6H11 (3) and the bidentate Ru (II) complex [Ru{pyCH2N(R)}C6H6]PF6 (R = C6H5 (4)) are reported. It was found that complexes 1, 2, 3 and 4 crystallised as mono-metallic species, with a piano stool geometry around each Ru centre. All complexes were active in the selective oxidation of n-octane using t-BuOOH and H2O2 as oxidants. Complexes 2 and 4 reached a product yield of 12% with t-BuOOH as oxidant, however, superior yields (23–32%) were achieved using H2O2 over all systems. The selectivity was predominantly towards alcohols (particularly 2-octanol) over all complexes using t-BuOOH and H2O2 after reduction of the formed alkylhydroperoxides in solution by PPh3. High TONs of up to 2400 were achieved over the Ru/H2O2 systems.
Synthesis of Co(II) NNN-pyridine based complexes and their activity in the partial oxidation of n-octane
Chanerika, Revana,Friedrich, Holger B.,Shozi, Mzamo L.
, (2019/07/12)
A series of four NNN-pyridine based ligands of the general form: pyCH2N(R)CH2py {R = propyl, tert-butyl, cyclohexyl and phenyl; py = pyridine} were synthesised and characterised. Complexation of each ligand to CoCl2?6H2O afforded new Co(II) complexes [Co{pyCH2N(R)CH2py}Cl2] (R = C3H7 (1), C(CH3)3 (2), C6H11 (3) and C6H5 (4)). Single crystal X-ray diffraction data confirmed that complex 1 crystallised as a mononuclear unit and was characterised by a distorted trigonal bipyramidal arrangement of ligands around Co. As catalysts in the oxidation of n-octane using t-BuOOH as oxidant, 2 (10% product yield) was found to be most efficient and the selectivity over 1–4 was predominantly towards 2-octanol, after reduction of alkylhydroperoxides by PPh3. All catalysts were significantly more active in the activation of n-octane using hydrogen peroxide, with a yield of 45% observed over catalyst 3. Furthermore, with H2O2, all catalysts produced a high concentration of alkylhydroperoxides, with catalyst 4 giving up to 91% alcohols after workup. TONs of up to 1100 were achieved over the Co/H2O2 systems.
Symmetric triazolylidene Ni(II) complexes applied as oxidation catalysts
Mncube, Siyabonga G.,Bala, Muhammad D.
, p. 467 - 473 (2018/11/06)
A set of related Ni(II) complexes of N-heterocyclic carbene ligands (NHC) [trans-X2Ni(NHC)2] (X = Cl, I) bearing linear straight chain alkyl wingtip substituents have been synthesised and fully characterised. Single crystal XRD data revealed symmetrically aligned Ni(II) centres within square planar coordination of trans halide, trans NHC ligands. The complexes were used for the catalytic oxidation of alkanes under mild conditions in conjunction with tert-butyl hydroperoxide as an oxidant. Under optimised reaction conditions, the catalytic results pointed to good activities of circa 15% and 19% for cyclohexane and n-octane respectively. Furthermore, the catalytic systems are shown to be very efficient for the oxidation of linear alcohols to corresponding ketones.
Synthesis, structural characterization and C–H activation property of a tetra-iron(III) cluster
Dey, Dhananjay,Patra, Moumita,Al-Hunaiti, Afnan,Yadav, Hare Ram,Al-mherat, Afrah,Arar, Sharif,Maji, Milan,Choudhury, Angshuman Roy,Biswas, Bhaskar
, p. 220 - 226 (2019/01/05)
A non-heme tetra-iron cluster, [Fe4 III(μ-O)2(μ-OAc)6(2,2′-bpy)2(H2O)2](NO3 ?)(OH?) (1), [OAc = acetate; 2,2′-bpy = 2,2′-bipyridine] containing oxido- and acetato-bridges was synthesized and structurally characterized by different spectroscopic methods including single crystal X-ray diffraction studies. X-ray crystal structure analysis of 1 revealed that tetra-iron complex was crystallized in monoclinic system with C2/c space group. Each of the Fe centres in 1 was found to exist in octahedral geometry and interconnected by oxido- and acetato-bridges. Bond valence sum (BVS) calculation recommended the existence of iron centres in +3 oxidation state. Variable temperature magnetic measurement authenticated the dominating antiferromagnetic ordering among the iron centres in the solid state of 1. This tetra-iron cluster was also evaluated as an efficient catalytic system towards the oxidation of both linear & cyclic alkanes without production of primary C–H bond oxidation products. Oxidation of secondary C–H bonds attested the formation of both the corresponding alcohols & ketones in 27–900 TONs. The tetra-iron catalytic system with Alcohol/Ketone values 0.2–1.7 indicated the involvement of freely diffusing carbon-centered radicals rather than metal based oxidant.
